For two years, police had suspected Caroline Nilsson of having been involved. However, they only arrested her last month, after examining the data from the watch.

Her claim was that her mother-in-law had been followed by a group of men and had argued with them for around 20 minutes outside her home.

Caroline Nilsson, who has been charged with her mother-in-law's murder, said she had been tied up in the home by the alleged intruders. She said she'd raised the alarm immediately after the attackers left.

More Technically Incorrect

"The evidence from the Apple iWatch [sic] is a foundational piece of evidence for demonstrating the falsity of the defendant's account to police," prosecutor Carmen Matteo reportedly said in court.

In addition, she said, there was no DNA evidence that any attackers had been in the home. Moreover, while Caroline Nilsson had claimed that the men had arrived in a utility vehicle, neighbors said they had seen no vehicle of that kind parked outside the house.

Apple didn't immediately respond to a request for comment.

A spokeswoman for the South Australia Police Department told me: "It is not South Australia Police policy to comment on matters which are currently before the courts."

She also offered me the words of Superintendent Des Bray, the officer in charge of major crime for the police department, before the case came to court. He said: "Police would like to reassure the community that that was not a random incident and not a home invasion."

This isn't the first time an advanced gadget has been used by police to obtain evidence. Two years ago, police in Arkansas asked for access to an Amazon Echo that they hoped would provide recordings in a home in which a man had been found strangled in the bath.